A team of international researchers found evidence that the herpes zoster (HZ) vaccination prevents or delays dementia. 

Led by Stanford University’s Dr Michael Pomirchy, a social scientist, the team used the data of 18,402 patients aged 70–79 years of age who were eligible for the Zostavax vaccine in Australia. Corroborating findings from a similar quasi-experiment in Wales, researchers said they found that being eligible for HZ vaccination based on date of birth significantly reduced the incidence of new dementia diagnoses by 1.8% (95% CI, 0.4-3.3; P = 0.01) during a 7.4-year follow-up period. 

Reactivations of the varicella zoster virus have been linked to long-lasting cognitive impairment, said researchers, writing in in JAMA. “Additionally, there is a substantial body of evidence suggesting that the herpes simplex virus may contribute to the development of dementia, along with suggestive evidence that reactivations of the varicella zoster virus may lead to reactivations of the herpes simplex virus in the brain.”